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How are mountains formed?

Folded rocksFolded rocksMoving tectonic plates are responsible for some of the Earth’s major landscape features. If a large slab of the Earth’s surface is gradually squeezed, the solid rock slowly wrinkles and crumples. Layers of rock become wavy folds. If the rocks are stretched, they may crack or split apart. These cracks are known as faults.

A diagram showing the collision of two tectonic platesA diagram showing the collision of two tectonic plates

Mountain building

When two tectonic plates push together, the rocks slowly crumple and fold up. This is how mountain chains are created. It happens over millions of years—far too slowly for us to notice. 

The Himalayas as seen from spaceThe Himalayas as seen from spaceThe world’s great mountains, including the Himalayas in Asia, Andes in South America, Rockies in North America and Alps in Europe, are all fold mountains. The Himalayas are actually getting higher, as two tectonic plates continue to push against one another. 

The tops of some mountains are so high that they are covered in snow and ice all year round. There is less oxygen in the air to breathe.


The Himalayan mountains grow taller by about the length of your thumb every year.
